Adhesive dispensing apparatus



March 8, 1966 J. 5. KELLEY ADHESIVE DISPENSING APPARATUS 5 Sheets-Sheet 1 Filed Oct. 15, 1963 g a nK nm fwm s Atzo rney W14 March 8, 1966 J. 5. KELLEY 3,239,103

ADHESIVE DISPENSING APPARATUS Filed Oct. 15. 1963 3 Sheets-Sheet 2 March 8, 1966 J. s. KELLEY 3,239,103

ADHESIVE DISPENSING APPARATUS Filed Oct. 15, 1963 3 Sheets-Sheet 5 United States Patent 3,239,103 ADHESIVE DISPENSING APPARATUS John S. Keiley, Wenham, Mass, assignor to United Shoe Machinery Corporation, Boston, Mass., a corporation of New Jersey Filed (Bet. 15, 1963, Ser. No. 316,241 7 Claims. (Cl. 222-56) This invention relates to apparatus for dispensing adhesive and particularly to apparatus of this type wherein molten thermoplastic adhesive is supplied at a substantially constant rate to a metering device which controls the flow of molten adhesive to an applicator nozzle, or equivalent dispensing device, at selected rates varying from a predetermined minimum up to a maximum substantially equal to the constant rate of supply. As herein illustrated the adhesive dispensing apparatus of this invention is shown as embodied in a portable adhesive dispensing apparatus adapted to be moved from place to place and operatively associated with another machine. It will, of course, be understood that in its broader aspects the invention is not limited to embodiment to this particular kind of adhesive dispensing apparatus or to the exact mechanical construction shown.

In the dispensing of so-called thermoplastic, or hot melt, adhesives it is frequently desirable to provide for the delivery of molten adhesive through a nozzle, or similar dispensing device at various different rates ranging from a predetermined minimum, which may be zero, up to a predetermined maximum. Presently available apparatus for melting and delivering molten adhesives, however, usually are not of a character to accommodate variations in the rate of delivery but instead operate more efficiently at some constant delivery rate. It is therefore an object of this invention to provide a relatively simple and inexpensive apparatus whereby molten adhesive may be efficiently and effectively delivered at various rates as may be required by different working conditions. With this object in view and in accordance with features of this invention, the herein illustrated apparatus which includes a device for melting and feeding molten adhesive having a driven member for delivering the molten adhesive at a predetermined rate and a nozzle, or equivalent device for dispensing the molten adhesive to a work piece, is provided with means for controlling the flow or molten adhesive from the melting and feeding device to the nozzle and thus varying the rate of flow of adhesive through the nozzle together with means for controlling the operation of the driven member of the melting and feeding device so as to stop and start the delivery of molten adhesive in accordance with the rate at which it is being delivered through the nozzle.

More particularly, in the herein illustrated apparatus the melting and feeding device includes means for feeding a solid rod of adhesive at a predetermined rate and a rotary member for melting the leading end of the solid rod of thermoplastic adhesive and for delivering the molten adhesive under pressure at a rate determined by the rate of feed of the solid rod while a positive displacement gear pump is provided for controlling the flow of molten adhesive to the nozzle together with means for driving the pump at different speeds to vary the flow through the nozzle from a predetermined minimum to a predetermined maximum rate. Moreover, in the herein illustrated apparatus the melting and feeding device is connected to the pump by means including a chamber having a wall portion which is movable, against a substantially constant force, to increase the volume of the chamber, and mechanism is provided which is responsive to changes in the volume of the chamber, as indicated by movements of the movable wall, for controlling the operation of the power 3,239,103 Patented Mar. 8, 1966 means for driving the rod feeding means and the rotary member of the melting and feeding device to start and stop delivery of molten adhesive and thereby to maintain the pressure of molten adhesive within the chamber and also at the gear pump substantially constant, regardless of variations of the rate of flow of the adhesive through the nozzle.

The above and other objects and features of the invention will appear in the following detail description of the preferred embodiment which is illustrated in the accompanying drawings and will be pointed out in the claims.

In the drawings,

FIG. 1 is a view in perspective of a portable dispensing apparatus embodying features of this invention;

FIG. 2 is a view in side elevation of the apparatus shown in FIG. 1 with a portion of the exterior housing broken away to expose elements contained therein;

FIG. 3 is a view in side elevation similar to that of FIG. 2 but showing only a portion of the apparatus and with parts in vertical section;

FIG. 4 is a detail view of a heated conduit forming part of the apparatus; and

FIG. 5 is a schematic diagram of an electrical system associated with the apparatus.

Referring to the drawings, an adhesive apparatus embodying the features of this invention is shown as applied to a portable device comprising a housing indicated generally by the reference character 10 of suitable construction and of the general configuration shown in FIG. 1, which housing is supported on casters 12, 12 and has upper and lower portions separated by a transverse plate or platform 14, FIG. 2. As can be seen in FIG. 1, various control members and indicating devices, some of which will be referred to below, are mounted on an inclined front wall 16 of the upper portion of the housing, while bracket members 18, 18 for supporting supply coils 20, 20 of rod-like thermoplastic adhesive are carried on the top of the housing. As will presently appear, molten ad hesive is dispensed through a nozzle 22, associated with a nozzle block 24 to which the molten adhesive is supplied through a heated conduit 26. It will be understood, of course, that the portable device is moved into a convenient location adjacent to a parent machine with which it is to be used and that the nozzle block 24 is then clamped to a portion of the parent machine, or otherwise secured in place in such a way as to present the nozzle in proper operative relation to the work pieces to be treated.

Referring now especially to FIGS. 2 and 3, there is mounted on the plate or platform 14, a thermoplastic adhesive melting and feeding unit of the same general construction as that disclosed in United States Letters Patent No. 2,765,768, issued October 9, 1956 in the name of Hans C. Paulsen (see especially FIG. 13 thereof). Thus, this unit includes a melting and feeding disk 30 rotatably mounted within a chamber 32 formed in a casing 34 into which the leading end of a solid rod of adhesive R is fed at a predetermined rate by means of feed wheels 36, 38. The melting and feeding disk is associated with a shaft 40 which also carries a sprocket 42, and associated with this shaft is another sprocket 44 and a magnetic clutch 46, FIG. 2. The feed wheels are arranged to be driven from the sprocket 42 by a chain 48, while the sprocket 44 and one element of the clutch 46 are arranged to be driven from an electric motor 50 through a suitable gear reduction unit, not shown but contained within a housing portion 52, a sprocket 54 and a chain 56. When the magnetic clutch 46 is energized,

in a manner to be explained below, the solid rod adhesive a discharge orifice 58. The speed of rotation of the feed wheels and melting and feeding disk will be such that the solid rod of adhesive is fully melted and delivered at the desired temperature. Thus the melting and feeding unit will be operated at its most efficient speed.

The discharge orifice 58 opens into one end 'of a passageway 60 formed in a header block 62 which is fastened at one end to the casing 34 of the melting and feeding unit, while its other end is supported on the platform by a post 64. The passageway 66 extends entirely through the header block and its other end is connected to the inlet passage 70 of a gear pump casing 72 by means of a suitable fitting 74. Adjacent to this end, the passageway so is in communication with a bore 7 6 formed in an upwardly extending portion 78 of the header block 62. Midway of its length, the bore 60 is enlarged to provide a seat for a spring-loaded check valve 80. The casing 72. contains the two meshing gears 82, 84 of the gear pump, one of which gears is carried by a shaft 86, FIG. 2. This shaft, and thus the two gears, are driven from an electric motor 88 through a suitable gear reduction, not shown but contained within a housing 90, sprockets 92, 94, and a chain 96. One end of the heated conduit 26 is connected, by means of a suitable fitting 98, to the discharge passage 160 of the gear pump.

Slidably received within the bore '76 is a piston rod 1tl2 which extends upwardly through a gland 103 and secured to this piston rod, above the portion 73 of the header block at, are two spaced-apart arms 104, 106. At its upper end, the piston rod 102 carries a pin 10% which is of slightly less diameter than the rod and which is adapted to fit into the bore 110 of a suitable counterweight 112. As will be apparent, the bore 76 and the piston rod 1162 provide a chamber of variable volume which will change as the piston rod moves upwardly or downwardly within the bore. Mounted on a bracket 114- secured to the upwardly extending portion 78 of the header block 6%, is an electrical switch 116 having two actuating plungers 120, 122 adapted to be engaged, respectively, by the arms 104, 1%, carried by the piston rod 102. As is diagrammatically illustrated in FIG. 5, the switch 116 is in a circuit leading from a DC. power source to a coil 124 associated with the magnetic clutch 46, and the arrangement is such that this clutch will be energized as the result of the engagement of the arm 106 with the plunger 122 of the switch 116, thus to start operation of the melting and feeding unit, while the clutch 46 will be deenergized, as a result of the engagement of the arm 104 with the plunger 120, thus to stop the operation of the melting and feeding unit.

The motor 88 is a variable speed D.C. motor of the type in which the speed of rotation may be varied by changing the field current. In FIG. two different arrangements for varying the current supplied to the field of the motor 88, through leads 130, 132, are shown. The first of these arrangements comprises a variable resistance R-l of a known type which may be adjusted manually, as for example by means of a knob K-l conveniently located on the inclined front wall of the housing 10, while the other arrangement includes a direct current generator, or tachometer, indicated generally by the reference character T and having a pick-up roller or wheel W adapted to be driven directly from a moving shaft or gear forming a part of the drive mechanism of the parent machine. A manually operable switch S1, diagrammatically illustrated in FIG. 5, is arranged to connect the leads 130, 132 either to the DC). line through the variable resistance R-l or to leads 134, 136 from the tachometer T. The motor 50 is a constant speed AC. motor which is connected to a suitable source of alternating current, not shown.

The rod adhesive melting and feeding unit, the header block, the gear pump casing, the heating conduit 26, and the nozzel block 24 are each maintained at suitable temperatures by means of appropriately located electrical heaters controlled by thermostats in the usual way, some of which are shown in FIG. 2. Various control knobs, off-on switches, signal lights, etc., associated with this electrical heating system, are conveniently located on the inclined wall 16 of the housing It Inasmuch as this heating system is more or less conventional, and since it forms no part of the present invention, further detailed description is deemed to be unnecessary.

As suggested above, in use the portable device shown in FIG. 1 is moved to a convenient location adjacent to a parent machine, and the nozzle block 24 is clamped to a part of the machine in position to apply molten adhesive to work pieces as they are fed past the nozzle by drive mechanism associated with the parent machine. A switch 8-2 associated with the motor 88 will be closed to start the gear pump 82, 84 in operation at a speed determined by the setting of the variable resistance R4, or by the tachometer T in accordance with the speed of the parent machine. Also, another switch, not shown, but associated with the motor 59, will be closed, thereby putting the adhesive melting and feeding unit into operation.

The speed of the motor is such that the melting and feeding disk 30 and feed wheels 36, 38 are rotated at speeds such that the volumetric output of molten adhesive into the passageway 6th is just slightly greater than the maximum volumetric rate at which the gear pump 82, 84, which serves as a metering device, can deliver molten adhesive from the passageway to the nozzle 22 through the heated conduit 26, when the motor 83 is operating at its highest speed. Therefore, so long as the melting and feeding unit is in operation there will be more adhesive delivered into the passageway 6i than is taken away from this passageway by the gear pump. This excess of molten adhesive will enter the chamber which is formed by the bore 76 and lower end of the piston rod 102 and will gradually force the piston rod upwardly, i.e., effect movement of the movable wall of this chamber.

When the piston rod reaches the position in which it is shown in FIG. 3, however, the arm 104 carried by the rod will engage the plunger 129 of the switch 116, thereby deenergizing the coil 124- of the clutch 46 to stop the operation of the adhesive melting and feeding unit. Now, as the gear pump continues to take molten adhesive away from the passageway 60, the piston rod 102 will be forced downwardly by the action of gravity of the counterweight 112 until the arm 106 engages the plunger 122 of the switch 116, thereby reenergizing the coil 124 of the clutch 46 to start the adhesive melting and feeding unit into operation again. These actions are repeated so long as the motors 5t) and 88 are in operation and the frequency of repetition of these actions will, of course, depend on the relative rates at which molten adhesive is delivered to the passageway 60 by the melting and feeding unit and taken away from this passageway by the gear pump. However, the pressure of the adhesive as received by the gear pump will remain constant because of the action of the counterweight 112 and the check valve 80. Therefore, the output of this gear pump will be determined solely by the speed of rotation of its gears 82, 84, as controlled either manually by the variable resistance R-ll or automatically from the parent machine by means of the tachometer T. Moreover, when the adhesive melting and feeding unit is in operation, it will be operating at a constant and most eflicient speed.

Having thus described my invention, what I claim as new and desired to secure by Letters Patent of the United States is:

1. Apparatus for dispensing molten adhesive comprising adhesive melting and feeding means including a rotary member for delivering molten adhesive at a predetermined rate, a nozzle for applying molten adhesive, means for controlling the flow of molten adhesive from said melting and feeding means to said nozzle adapted to vary the fiow through the nozzle from a predetermined minimum to a predetermined maximum rate, power operated means for driving the rotary member of said melting and feeding means at a constant speed sufficient to provide for delivery of molten adhesive by said melting and feeding means at a rate in excess of the predetermined maximum rate provided by said flow controlling means, and means for controlling the operation of said driving means adapted to maintain the pressure of molten adhesive delivered to the flow controlling means substantially constant as the flow through said flow controlling means is varied between said predetermined minimum and maximum rates.

2. Apparatus for dispensing molten adhesive comprising melting and feeding means including a rotary member for delivering molten adhesive at a predetermined rate, a nozzle for applying molten adhesive, a positive displacement gear pump for controlling the flow of molten adhesive, and means for driving the pump at different speeds for controlling the flow of molten adhesive from said melting and feeding means to the nozzle to vary the flow through the nozzle from a predetermined minimum to a predetermined maximum rate, power operated means for driving the rotary member of said melting and feeding means at a constant speed sufiicient to provide for delivery of molten adhesive by said melting and feeding means in excess of the predetermined maximum rate provided by said gear pump, and means for controlling the operation of said last-named driving means adapted to maintain the pressure of molten adhesive delivered to the gear pump substantially constant as the flow is varied between said predetermined minimum and maximum rates.

3. Apparatus for dispensing molten adhesive comprising adhesive melting and feeding means including means for feeding a solid rod of thermoplastic adhesive and a rotary member for melting the leading end of the solid rod of adhesive and for delivering molten adhesive at a predetermined rate, a nozzle for applying molten adhesive, a positive displacement gear pump for controlling the flow of molten adhesive, and means for driving the pump at different speeds for controlling the flow of molten adhesive from said melting and feeding means to the nozzle to vary said flow through the nozzle from a predetermined minimum to a predetermined maximum rate, power operated means for driving the rotary member of said melting and feeding means at a constant speed sufficient to provide for delivery of molten adhesive by the melting and feeding means in excess of the predetermined maximum rate provided by said gear pump, and means for controlling the operation of said last-named driving means adapted to maintain the pressure of molten adhesive delivered to the gear pump substantially constant as the flow is varied between said predetermined minimum and maximum rates.

4. Apparatus for handling thermoplastic adhesive comprising a melting and feeding unit having means for melting and feeding thermoplastic adhesive, including a driven member for delivering molten adhesive at a predetermined rate, a nozzle for applying molten adhesive to a work piece, a positive displacement pump for controlling the flow of molten adhesive from said melting and feeding unit to said nozzle, means for driving the pump at different speeds to vary the rate of flow of molten adhesive through the nozzle, means connecting the melting and feeding unit to said pump including means providing a chamber of variable volume, and mechanism responsive to changes in the volume of said chamber for controlling the operation of said driven member thereby to start and stop delivery of molten adhesive from the melting and feeding unit into said chamber.

5. Apparatus for handling thermoplastic adhesive comprising a melting and feeding unit having means for melting and feeding thermoplastic adhesive, including a driven member for delivering molten adhesive at a predetermined rate, a nozzle for applying molten adhesive to a work piece, a positive displacement pump for controlling the flow of molten adhesive from said melting and feeding unit to said nozzle, means for driving the pump at different speeds to vary the rate of flow of molten adhesive through the nozzle, means connecting the melting and feeding unit to said pump including means providing a chamber of variable volume, said chamber including a wall portion movable against a substantially constant and yieldable force, and mechanism responsive to changes in the volume of said chamber as indicated by movements of the movable wall portion for controlling the operation of said driven member thereby to start and stop delivery of molten adhesive from the melting and feeding unit into said chamber.

6. Apparatus for handling thermoplastic adhesive comprising a melting and feeding unit having means for feeding a solid rod of thermoplastic adhesive, means for melting the leading end of the solid rod as it is received, and means including a driven member for delivering molten adhesive at a predetermined rate, a nozzle for applying molten adhesive to a work piece, a positive displacement pump for controlling the flow of molten adhesive from said melting and feeding unit to said nozzle, means for driving the pump at dilferent speeds to vary the rate of flow of molten adhesive through the nozzle, means connecting the melting and feeding unit to said pump includ ing means providing a chamber of variable volume, and mechanism responsive to changes in the volume of said chamber for controlling the operation of said driven member thereby to start and stop delivery of molten adhesive from the melting and feeding unit into said chamber.

7. Apparatus for handling thermoplastic adhesive comprising a melting and feeding unit having means for feeding a solid rod of thermoplastic adhesive, means for melting the leading end of the solid rod as it is fed, and means including a driven member for delivering molten adhesive at a predetermined rate, a nozzle for applying molten adhesive to a work piece, a positive displacement pump for controlling the flow of molten adhesive from said melting and feeding unit to said nozzle, means for driving the pump at different speeds to vary the rate of flow of molten adhesive through the nozzle, means connecting the melting and feeding unit to said pump including means providing a chamber of variable volume, said chamber including a Wall portion movable against a substantially constant and yieldable force, and mechanism responsive to changes in the volume of said chamber as indicated by movements of the movable wall portion for controlling the operation of said rod feeding means and said driven member thereby to start and stop delivery of molten adhesive from the melting and feeding unit into said chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,859,290 5/1932 Davis ZZZ-56 1,902,750 3/1933 Barks 222-56 2,149,127 2/1939 Tear 22256 2,218,390 10/1940 Alexander 222-56 2,765,768 10/1956 Paulsen 222146 X LOUIS J. DEMBO, Primary Examiner. RAPHAEL M. LUPO, Examiner. 

1. APPARATUS FOR DISPENSING MOLTEN ADHESIVE COMPRISING ADHESIVE MELTING AND FEEDING MEANS INCLUDING A ROTARY MEMBER FOR DELIVERING MOLTEN ADHESIVE AT A PREDETERMINED RATE, A NOZZLE FOR APPLYING MOLTEN ADHESIVE, MEANS FOR CONTROLLING THE FLOW OF MOLTEN ADHESIVE FROM SAID MELTING AND FEEDING MEANS TO SAID NOZZLE ADAPTED TO VARY THE FLOW THROUGH THE NOZZLE FOR A PREDETERMINED MININUM TO A PREDETERMINED MAXIMUM RATE, POWER OPERATED MEANS FOR DRIVING THE ROTARY MEMBER OF SAID MELTING AND FEEDING MEANS AT A CONSTANT SPEED SUFFICIENT TO PROVIDE FOR DELIVERY OF MOLTEN ADHESIVE BY SAID MELTING AND FEEDING MEANS AT A RATE IN EXCESS OF THE PREDETERMINED MAXIMUM RATE PROVIDED BY SAID FLOW CONTROLLING MEANS, AND MEANS FOR CONTROLLING THE OPERATION OF SAID DRIVING MEANS ADAPTED TO MAINTAIN THE PRESSURE OF MOLTEN ADHESIVE DELIVERED TO THE FLOW CONTROLLING MEANS SUBSTANTIALLY CONSTANT AS THE FLOW THROUGH SAID FLOW CONTROLLING MEANS IS VARIED BETWEEN SAID PREDETERMINED MINIMUM AND MAXIMUM RATES. 